### What does this PR do?
This PR upgrades the `react-shadcn` template:
- Upgrades to the new Tailwind v4 styles and components
- Updates the example components to use the new ones.
- Removed unused form component
- Fixed some a11y issues with the example component.
### How did you verify your code works?
- Ran `bun build` to test if the template builds with no errors.
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Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
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